Support for TURN/TLS.
Support for TURN/TLS.

Wrap the socket in an SSL adapter, then simply call StartSSL() on the
SSLAdapter instance.

Cloned from: https://webrtc-codereview.appspot.com/21799004/

R=juberti@chromium.org, juberti@webrtc.org
BUG=

Review URL: https://webrtc-codereview.appspot.com/14059004

Patch from Manish Jethani <manish.jethani@gmail.com>.

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: c8554be6dd41c6fe48eb6b09e9cfc0fb0064a7ff

sippet/talk,sippet/talk,sippet/talk,sippet/talk,sippet/talk